Cement restrictor system and method of forming a cement plug within the medullary canal of a bone

Abstract

A cement restrictor system is provided for making a cement plug within the medullary canal of a long bone. The system includes an inflatable body, a conduit having first and second ends that defines a fluid passage to and from the inflatable body, and a shield releasably securable to the conduit. In an exemplary method of making a cement plug with the system an obstruction, such as the shield, is placed in a medullary canal of a long bone beyond the isthmus of the long bone. The obstruction is held in place with the flatable body. A predetermined quantity of bone cement is poured into the medullary canal and localized by the obstruction. The bone cement is allowed to harden; and the conduit and inflatable body are removed from the bone.

What is claimed is: 
     
       1. A cement restrictor system for providing a cement bone plug in the medullary canal of a bone, comprising: an inflatable body;   a conduit having a first end and a second end, the conduit defining a fluid passage to the to the inflatable body for inflating and deflating the inflatable body; and   a shield releasably securable to the conduit, the shield having a proximal surface for impeding the flow of bone cement and a distal surface for abutting the inflatable body, the shield and inflatable body being insertable in the medullary canal to form a seal therein allowing the formation of the cement bone plug adjacent the shield.   
     
     
       2. The cement restrictor system of claim 1, wherein the shield extends radially outward from the conduit. 
     
     
       3. The cement restrictor system of claim 2, wherein the proximal surface of the shield includes a plurality of protuberances extending therefrom for promoting adhesion of the bone cement to the shield. 
     
     
       4. The cement restrictor system of claim 3, wherein each of the protuberances includes a stalk having a first end secured to the shield and a second end having a greater diameter than the first end of the stalk. 
     
     
       5. The cement restrictor system of claim 2, wherein the promixal surface faces the first end of the conduit and is roughened. 
     
     
       6. The cement restrictor system of claim 1, wherein the shield is located at a point between the first end of the conduit and the inflatable body. 
     
     
       7. The cement restrictor system of claim 1, wherein the conduit includes: a rigid tubular guide having a first end and a second end, the second end being releasably securable to the shield, and   a flexible catheter having a first end and a second end, the flexible catheter being disposed at least partially within the tubular guide,   wherein the inflatable body surrounds a portion of the catheter between the shield and the second end of the conduit.   
     
     
       8. The cement restrictor system of claim 7, further including a radiopaque element proximate the second end of the flexible catheter. 
     
     
       9. The cement restrictor system of claim 7, further including a plurality of measurement indicia on an exterior portion of the rigid tubular guide. 
     
     
       10. The cement restrictor system of claim 1, wherein the shield defines an obstruction surface having a diameter greater than the diameter of an isthmus of a selected bone, and wherein the inflatable body is inflatable to a diameter greater than the diameter of the shield. 
     
     
       11. The cement restrictor system of claim 1, further comprising a collar that is positionable proximate the shield to define a space between the shield and the collar. 
     
     
       12. The cement restrictor system of claim 11, further comprising a cement supply tube for directing cement into the space between the shield and the collar. 
     
     
       13. The cement restrictor system of claim 12, wherein the cement supply tube is secured to the collar. 
     
     
       14. A cement restrictor system comprising: an inflatable body;   a conduit having a first end and a second end, the conduit defining a fluid passage to the inflatable body; and   a shield releasably securable to the conduit, the shield extending radially outward from the conduit, wherein the shield includes a frustroconical body that is flexible at its periphery.   
     
     
       15. The cement restrictor system of claim 14, wherein the frustroconical body includes sealing structure that defines an aperture through the shield. 
     
     
       16. The cement restrictor system of claim 15, wherein the sealing structure includes two opposed flexible elements. 
     
     
       17. A cement restrictor system comprising: an inflatable body;   a conduit having a first end and a second end, the conduit defining a fluid passage to the inflatable body; and   a shield releasably securable to the conduit,   wherein the conduit includes: a rigid tubular guide having a first end and a second end, the second end being releasably securable to the shield, and   a flexible catheter having a first end and a second end, the flexible catheter being disposed at least partially within the tubular guide,   wherein the inflatable body surrounds a portion of the catheter between the shield and the second end of the conduit and the flexible catheter and the inflatable body can be passed through the rigid tubular guide from the second end of the rigid tubular guide to the first end of the rigid tubular guide.     
     
     
       18. A cement restrictor system comprising: a rigid tubular guide having a first end and a second end;   a flexible catheter having a first end and a second end, the flexible catheter being positionable at least partially within the tubular guide, wherein the second end of the flexible catheter is extensible from the second end of the tubular guide;   an inflatable body surrounding a portion of the catheter proximate the second end of the catheter, wherein the catheter defines a fluid path to and from the interior of the inflatable body;   a flexible shield releasably securable to the rigid tubular guide at a point between the first end of the rigid tubular guide and the inflatable body; and   a collar that is positionable between the first end of the rigid tubular guide and the shield to define a space between the collar and the shield.   
     
     
       19. The cement restrictor system of claim 18, further including a cement supply tube for directing cement into the space between the shield and the collar, wherein the cement supply tube is securable to the collar. 
     
     
       20. A method of forming a cement plug comprising the steps of: placing a first obstruction in a medullary canal of a long bone beyond the isthmus of the long bone;   holding the first obstruction in place with an inflatable body such that first obstruction and the inflatable body form a seal in the medullary canal that is effective to prevent the flow of bone cement;   depositing a predetermined quantity of bone cement into the medullary canal; and   allowing the bone cement to harden to form a cement bone plug.   
     
     
       21. The method of claim 20, further comprising the step of deflating the inflatable body and removing the inflatable body from the long bone after the step of allowing the bone cement to harden. 
     
     
       22. The method of claim 20, further comprising the step of placing a second obstruction in the medullary canal in a spaced apart relationship with the first obstruction to define a space, and wherein the step of depositing includes the step of depositing the predetermined quantity of bone cement into the space defined by the first obstruction and the second obstruction.